The present invention relates to an automatic loading method and mechanism for loading preformed parts, such as the stacked laminations of a motor rotor, into the die cavities of a die casting machine.
In the manufacture of squirrel cage rotors for electric motors, it is common practice to form them of a plurality of stacked, circular laminations each having a central opening and a plurality of openings positioned in a circular array near the peripheral edge of the lamination. The laminations are stacked on a stacking pin with a slight skew or no skew to the circular array of openings from one lamination to the next so that the openings collectively form a plurality of partially helical passages or channels axially through the stacked laminations.
These rotor preforms are then loaded into the die cavities of a die casting machine, and molten aluminum is injected into the cavity whereupon it flows through the skewed channels in the stack of laminations to form the conductor bars and to form end rings on opposite ends of the stack of laminations, which provide electrical interconnection between the conductor bars. The end rings may either be formed smooth or with fins for the purpose of cooling. The formed rotor is then removed from the die casting machine, and the stacking pins are pressed out so that the rotor assembly is held together by means of the cast aluminum end rings and conductor bars.
In the past, the rotor preforms have either been loaded into the die cavities by hand or by means of a cumbersome, complex rotary loader mechanism.